Recently, as a new memory device, a nonvolatile semiconductor memory device called ReRAM (Resistance Random Access Memory) is noted. The ReRAM uses resistance memory elements which have a plurality of resistance states of different resistance values and have the resistance states changed by external application of electric stimuli, and is used as a memory device by corresponding the high resistance state and the low resistance state of the resistance memory elements to, e.g., “0” and “1” of information. The ReRAM is very prospective because the ReRAM can realize the high speed, large capacities, low electric power consumption, etc.
The resistance memory element includes a resistance memory material whose resistance state is changed by the application of voltages sandwiched between a pair of electrodes. As the typical resistance memory material is known the transition metal content oxide material.
Related references are as follows:    Patent Reference 1: Japanese Laid-open Patent Publication No. 2004-213744    Non-Patent Reference 1: I. G. Baek et al., “Highly Scalable Non-volatile Resistance Memory using Simple Binary Oxide Driven by Asymmetric Unipolar Voltage Pulses”, IEDM 2004    Non-Patent Reference 2: S. Seo et al., “Conductivity switching characteristics and reset currents in NiO films”, Applied Physics Letters 86, 093509 (2005)    Non-Patent Reference 3: K. Kinoshita et al., “New Model Proposed for Switching Mechanism of ReRAM”, IEEE NVSMW 2006, p. 84-85